The present invention relates to a method for manufacturing a semiconductor apparatus, and more particularly to a hardening temperature profile of a paste material applied to a lead-frame at a die bonding process.
A procedure for manufacturing a semiconductor apparatus comprises a die bonding process of applying a paste material to a die-pad of a lead-frame and then attaching a chip part formed of a semiconductor to the lead-frame by pressure, and a thermally hardening process of leaving the lead-frame and the chip part for a predetermined time at a high temperature of about 100 to 250.degree. C. and hardening the paste material between the lead-frame and the chip part to fix the chip part and the lead-frame to each other.
Conventionally, a lead-frame formed of a ferroalloy which mainly comprises iron referred to as a "42 alloy" has been used for the lead-frame of the semiconductor apparatus (hereinafter referred to as a "Fe lead-frame"). In recent years, a lead-frame formed of a copper alloy which mainly comprises copper has been used (hereinafter referred to as a "Cu lead-frame").
However, there is a problem that various bonding failures are caused as shown in FIGS. 7 (a) and 7 (b) at the thermally hardening process of fixing the lead-frame and the chip part to each other by using a paste material including a thermosetting resin or the like.
More specifically, a chip--paste bonding failure is caused in which a paste material 103 between a lead-frame 101 and a chip part 102 peels off the chip part 102 as shown in FIG. 7 (a), or a cohesive failure is caused in which the paste material 103 bonded to the lead-frame 101 and the chip part 102 therebetween is broken as shown in FIG. 7 (b). In a Cu lead-frame 101A formed by laminating an outer metal layer 101a formed of palladium (Pd) or gold (Au) and an inner metal layer 101b formed of a copper alloy in order to enhance characteristics of the semiconductor apparatus, a lead-frame--paste bonding failure is easily caused in which the paste material 103 between the Cu lead-frame 101A and the chip part 102 peels off the Cu lead-frame 101A as shown in FIG. 7 (c).